Fuel question - e85 worth it?
 

Hello everyone, I have all of the parts to upgrade my NA8 Rotrex Miata in my quest for ~230whp when my friend just told me there’s an e85 fuel station 10 minutes from my house. I was unaware of this and thought the closest station was 50 miles east of me where I never travel… my big question here is - is it worth it? The station pumps out between e50&e69 according to my buddy. My car is track only and not street legal. My only cost to do this would be return my ff640 and buy ff900 or whatever the next size is. And maybe a new fuel pump for good measure. So I ask the all knowing… is e50-e69 good enough to make it so I need to do the hassle of make sure the car is filled before heading to the track? And get maybe 30-50 hp extra out of it? Guide me! I’d love the extra power for sure.
or are there other things I need? I have MSpnp2

Personally after experiencing e85 it's a no-brainer, especially for a track car. Not only will you be able to safely run more timing (more powah!), but the underhood temps are just cooler all around (including IAT's and CLT's). I think the only downside for a track car is that you'll run through a tank much quicker.

E50 is fine, IIRC you get most of the benefits of ethanol after about 40%. The only downside is that with ms2 I wouldn't mess with flex fuel, it's just pretty bad on MS2. I could be wrong there, but last time I looked into it it didn't seem worth it. I'd probably just tune for whatever you get at the PUMP and EGO should be able to correct for the % changes between 50-69%.

I'm in a super similar boat right now. Thought the only e85 was a ways away but realized there's one pretty close to my place.

Considering the car is track only I assume you have no intent to run flex fuel? Once converted it would be e85 only? That would simplify the tuning side, and you could always have a 91 tune to flash on if you couldn't get e85 for whatever reason.

Like Fire said above, there aren't any major downsides to running ethanol aside from having to fill up more often.

I agree with both of the above, but I’ll echo that FlexFuel in MS2 is not great. It will run, but it won’t be a smooth transition between the various ethanol contents. You will have to accept that one of the ethanol ranges will run well, while the other will be imperfect and rely on EGO Correction to make it right. Full throttle will probably be pretty close but cruise will be less than ideal, or viceversa. Might be more linear with a supercharger than the turbo cars I’ve messed with.

You might be better off having a 10%, 70%, and a 40% maps you can switch between, or switch to MS3/Link if budget allows and have proper FlexFuel

Are there any downsides other than consumption and availability?

Which station? The one in/near noho? Google reviews say that place sucks ass. Charlton is the only good source afaik in mass.

Ethanol is corrosive, so you don’t want to leave it in your tank unused for a long period of time or run the car for short periods without getting up to temperature. Check out this MotoIQ video:
If you run the engine up to temperature often then it’s fine. If you run the car in short trips or around a shop not getting up to temperature, then not ideal.

edit: when I say long periods, I mean months on end not running the engine. You don’t want the ethanol pooled in line and injectors either.

I have been running a stock motor @255whp on a mustang dyno for 30hrs now. It is tuned on 91 but I run 96oct. I run the thing real hard. I wish I did E85 earlier that way I could have saved so much money on fuel. It will also keep temps just lower in general. Id run it.

yes sir! My friend says it’s not reliable on the ethanol content. But he told me it’s a minimum of e50… who knows.

the other one is on the mass pike too far away.

Does your friend say how much they charge? The reviews 1-2 years ago say 6.50/gal.

It's 1hr20min round trip to noho vs 1hr40min to Charlton for me. Both aren't worth it so I've never made the switch for any of my cars.

I'd say even "crappy" e85 is worth it. Crappy e85 just has more gasoline in it, but if you are over 40% eth you get most of the cooling and knock suppression benefits anyways. It might not be worth if the % fluctuates too much and you are having issues adjusting for that, but otherwise the fuel itself is probably still worth it.

where are you that e85 saves you money? Here it’s roughly the same price as gasoline, but since you’re using ~40% more…it costs 40% more. Has to be ~60% the price of premium to break even with non-E,

Its $3.00 for 87/reg, $2.00 for E85 here in the midwest as of today. I would guess probably talking about the additives to get to 96- whether a can of octane booster or a splashes of 100 sunoco

Damn, that's a decent incentive. Helps that you're around all the corn fields. You'll notice where I am, in Oregon, there's near zero.

https://cimg2.ibsrv.net/gimg/www.mia...5120751130.png

YEAH BUT THEY MAKE US PUMP IT :) Back in college, i'd head south to Milton-Freewater every so often for that experience

Unfortunately my car sits for long periods of time, being in NE and it not being a street car, it sees 3-7 track days a year. And I’m not about to pump the tank out at the end of the season… so it sounds like it’s 93 for me! Too bad, would’ve loved 260-300 hp…

Fair enough. My car often sits for 3-4 months at a time on full e85 and I've never had issues. I'll usually start it a few times over the winter an heatcycle it, but nothing else special. I've been running e85 for 4 years or so.

With a good tune you should be able to get 300+ whp on pump 93 with no detonation. I was at 325whp with a GTX2867R on 93 and wasn't constrained by anything but injectors and a MAP sensor from going up from there.

For me it's not power, it's peace of mind that while hotlapping said 300whp car in the heat that it probably won't ever be able to det itself apart.

If only a few times a year, mix some sensor safe race fuel in it or maybe run it 100%.